Archive for December 15th, 2010

Electric Cars. Green? Only if painted that colour!

December 15, 2010

Electric cars are to be subsidised by tax payers to the tune of £5,000 per car. Who is likely to buy them? Those who commute to work, as their second car? Why should the cars be subsidised in the present economic climate when they are of little benefit as regards Green issues? Electric cars are NOT the answer.

Why electric cars are not the answer.

Firstly, cost. The fundamental problem with electric cars is the relatively low power density of batteries – when measured by volume or weight. This is improving, but the batteries are very expensive. They take a lot of energy to create, and another lot of energy to recycle – not to mention some rather obnoxious materials in them.

They are also slow to recharge – to the extent that there are now proposals for complex removable packs and automated battery swapping bays to allow ‘recharging’ by replacement. That requires a huge investment in facilities and spare batteries.

As to efficiency, instead of burning fuel at the point of use and converting it directly into mechanical energy, it’s burned at a power station, used to create steam, the steam then creates mechanical energy, that is converted to electrical energy, transmitted around the country, converted down again to charge the battery where it’s converted to chemical energy. Then at the point of use, the chemical energy is turned back into mechanical energy to drive the car. It might be worth pointing out that one of the reasons ships moved from steam to diesel is that diesel is more efficient thermodynamically and the efficiency of a diesel engine exceeds the theoretically achievable efficiency of a steam turbine.
So overall – is an electric car more efficient than a liquid fuelled one? After all those conversions, probably not.

So against battery, it takes a lot of energy and resources to make the batteries, it takes a lot to dispose of/recycle them at end of life, and they aren’t all that efficient in between.

Now lets look at practicalities. In this country we are reliant on fossil fuel for power generation – and that isn’t going to change in the near future. You can buy ‘green’ electricity, but don’t kid yourself that using extra ‘green’ electricity doesn’t result in more CO2 emissions – because every unit of ‘green’ electricity you buy and use to charge a car isn’t available to replace coal/oil/gas produced electricity being used by others. In other words, if you use a unit of electricity to charge your car, then somewhere a gas/oil/coal powered station has to turn it’s output up to create a unit to sell to someone else.

We are already reliant on imported energy – nuclear generated power from France, oil and gas from various places. If pretty well any of these suppliers were to turn off the switch, then we’d have a deficit and in all probability have a rolling blackout program (that’s how little reserve capacity and diversity we have now). Anyone recall the 70’s?

Add lots of electric cars to the grid – and it won’t be able to supply them. Try to charge a lot of them at once – and the distribution network couldn’t carry the extra load either in most places.

There are alternatives. Synthetic methanol production is just one – it’s a liquid fuel, easily transported and retailed using existing infrastructure, and new vehicles could be made ‘flex fuel’ by fairly minor changes for very little cost. It’s miscible (mixes with) petrol and ethanol in any proportion, and it’s actually safer in case of fire or spillage than petrol. It’s also less harmful than petrol if ingested or inhaled.
Being liquid it’s easily transported by non-pressurised tankers — including ships — so it can be made anywhere there is the power to produce it. All it needs is CO2 from the air, and hydrogen. If made in sunnier places, the hydrogen can be obtained by electrolytic cracking of water using photo-voltaic generated power. And overall, it is carbon neutral to create and use.